The Collaborative International Dictionary of English v.0.48:

Elector \E*lect"or\, n. [L., fr. eligere: cf. F. ['e]lecteur.]
   1. One who elects, or has the right of choice; a person who
      is entitled to take part in an election, or to give his
      vote in favor of a candidate for office.
      [1913 Webster]

   2. Hence, specifically, in any country, a person legally
      qualified to vote.
      [1913 Webster]

   3. In the old German empire, one of the princes entitled to
      choose the emperor.
      [1913 Webster]

   4. One of the persons chosen, by vote of the people in the
      United States, to elect the President and Vice President.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Elector \E*lect"or\, a. [Cf. F. ['e]lectoral.]
   Pertaining to an election or to electors.
   [1913 Webster]

         In favor of the electoral and other princes. --Burke.
   [1913 Webster]

   Electoral college, the body of princes formerly entitled to
      elect the Emperor of Germany; also, a name sometimes
      given, in the United States, to the body of electors
      chosen by the people to elect the President and Vice
      President.
      [1913 Webster]

WordNet (r) 3.0 (2006):

elector
    n 1: a citizen who has a legal right to vote [syn: voter,
         elector]
    2: any of the German princes who were entitled to vote in the
       election of new emperor of the Holy Roman Empire

Bouvier's Law Dictionary, Revised 6th Ed (1856):

ELECTOR, government. One who has the right to make choice of public officers
one, who has a right to vote.
     2. The qualifications of electors are generally the same as those
required in the person to be elected; to this, however, there is one
exception; a naturalized citizen may be an elector of president of the
United States, although he could not constitutionally be elected to that
office.



The Devil's Dictionary (1881-1906):

ELECTOR, n.  One who enjoys the sacred privilege of voting for the man
of another man's choice.